Molding assembly for internal combustion engine blocks



J. L.. FLITZ Aug. 9, 1966 MOLDING ASSEMBLY FOR INTERNAL COMBUSTION ENGINE BLOCKS 5 Sheets-Sheet 1 Filed Dec. 18, 1963 ATTORNEY 3 Sheets-Sheet 2 1 y NW7 3% my/O v ATTORNEY J. L. FLJTZ Aug. 9, 1966 MOLDING ASSEMBLY FOR INTERNAL COMBUSTION ENGINE BLOCKS Filed Dec. 18, 1963 Aug. 9, 1966 J. l... FLJTZ 3,264,693

United States Patent F 3,264,693 MOLDING ASSEMBLY FOR INTERNAL COM- BUSTION ENGINE BLOCKS John L. Flitz, Saginaw, Mich, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Filed Dec. 18, 1963, Ser. No. 331,442 6 Claims. (Cl. 22-131) This invention relates to sand casting internal c0mbustion engine blocks, and more particularly to a molding assembly having an improved core arrangement whereby such engine blocks may be more accurately formed than before.

Cast iron engine blocks are made in sand molds which are formed in metal flasks by ramming both the cope and the drag half with green sand around a pattern. The two flask halves are then assembled together after removal of the patterns to establish a mold cavity which generally defines the exterior surface configurations of the engine block. Baked sand cores are supported in spacial relationship within the cavity by wires, core print projections, or the like to define the interior surfaces of the block.

Some of the more undesirable aspects of sand casting come from the sand cores which are required to define interior spaces of the engine block. To form a block as many as twenty such cores may be required, some cores being glued together and assembled with others until the required interior shape is formed. Naturally a slight misalignment due to a shifting of sand cores being glued will be carried over as an error into the finished casting. Furthermore, such interior cores often require the use of support rods or chaplets to locate them in the mold and to prevent them from being floated out of position due to the buoyancy of the molten iron. These chaplets are intended to become an integral part of the casting, but if the bond is defective the casting may leak.

Core setting is also a major problem. In simple castings, the cores may be located by the core prints in the drag half of the mold, but in more complicated coring arrangements some sort of transfer fixture that prepositions the core assembly prior to placing it in the mold is required.

In the past, cast iron blocks required considerable machining and were relatively heavy units, not only due to the weight of cast iron, but also due to the thick walls required to achieve a structurally sound part.

The weight factor in the present day automobile has become such a sore point that lighter engine blocks have become attractive; hence there has been a shift recently to emphasize the light weight metals, such as aluminum alloys, which may be pressure die cast. Such a process does not require sand cores and inherently overcomes many of the defects heretofore plaguing the sand molding process. However, die casting of aluminum alloys, or

similar light metals, has its problems, too, due to the high cost of equipment and the troublesome metallurgical properties of these metals; hence the most recent trend is now a shift back towards cast iron for making engine blocks.

This re-evaluation of the cast iron block has been possible primarily through recent improvements in core assembly techniques and mold and core castings which allow more accurate, thin walled castings to be made. The former technique is disclosed in United States Patent 2,783,510 Dolza et al. In Dolza et al., the conventional methods of coring a V-type cylinder block were rendered obsolete by his advance which contemplates making the projections and depressions embracing the interior surfaces of the block so that a single core may be employed for each crankthrow compartment and associated cylinder cavity, the crankcase-barrel core units being formed in a core box the parting line of which would be in an imaginary plane passing transversely through the block and gen- 3,264,693 Patented August 9, 1966 erally through the axes of the cylinders. In other words, in the past where a separate core was required for each cylinder barrel and crankthrow area, the crankcase and barrel cores may be formed according to Dolza et al. in one piece while lying on their sides in a core box having a horizontal parting line through the center. A plurality of such crankcase and barrel core units, depending on the number of cylinders in the engine, can then be assembled, one behind the other, in the drag half of the mold with the various cooperating core elements arranged around them, thus greatly reducing the number of cores required and simplifying the procedure of core setting. The core setting step may be even further improved by the technique shown in the United States Patent 2,768,414 Dolza where a metal tray is used to prearrange the crankcase-barrel cores.

Due to the elimination of a great many core pieces and more accurate means for core setting, the accuracy of iron blocks has improved and the cost has been reduced. Following the trails blazed by Dolza in his patents, the present invention makes a significant contribution and improvement which it is believed makes sand casting even more advantageous for the manufacture of vehicle engine blocks.

In accordance with the present invention, a one piece crankcase-barrel core for all of the crankthrow and cylinder barrel spaces in the block is provided which comprises the basic core unit of an interfitting core assembly. The crankcase-barrel core unit is formed in a novel multipart core box including a plurality of fixed and relatively movable sections adapted to define a core mold cavity when in the closed position and having blow tubes for introducing a core sand mixture into the cavity under air pressure and vents for exhausting the cavity. The movable sections include a cover section with projections or blades adapted to be withdrawn from the core interior to render inner adjacent surfaces thereof exposed for cooperation With surfaces in the mold cavity to define the bulkhead and bearing structure of the engine block and a reciprocative barrel section for forming the barrel core portions movable relative to the cover section along the axes of the barrel core portions of the crankcase-barrel core unit.

Additional features and objects of this invention will be made clear by reference to the following detailed description and drawings wherein:

FIGURE 1 is an exploded perspective view of the one piece crankcase-barrel core showing it and other cores used to form a V-8 cylinder block for an internal combustion engine and the relationship of these cores with each other in accordance with the present invention;

FIGURE 2 is a perspective view of the drag and drag half of the mold shown ready to receive the core assembly in FIGURE 1;

FIGURE 3 is a perspective view of the drag shown in FIGURE 2 with the core assembly in place;

FIGURE 4 is a sectional view taken along the line 44 of FIGURE 3 through the mold with the cope in plate; showing the spacing of the core assembly in the mo FIGURE 5 is a sectional view of the core box for making the one piece crankcase-barrel core shown in the closed position; and

FIGURE 6 is an exploded perspective view of the movable core box sections.

Referring to FIGURES l4, a five-piece baked sand core assembly is provided which includes a unitized crankcase-barrel core 10, right and left water jacket cores 12 and 13, -a rear end core 14, and a front end core 16. The core assembly is positioned in the casting cavity of the drag half of the sand mold 18 shown in FIGURE 2 and having a bottom wall in which is formed a longitudinally extending elongated portion 20 which directly supports the crankcase-barrel core 16 and rear and 'front cores 14 and 16. The portion 20. is positioned to support the core assembly in spacial relationship within the mold cavity when the flask is closed and is formed along with" the drag half of the mold in the conventional manner by ramming green sand around a pattern having the shape of the drag cavity which defines the lower exterior walls of the block. After the drag half of the mold 18 has been rammed, the cope half 24 shown in FIGURE 4, is

likewise rammed with green sand about a pattern form-- ing the cope cavity defining the upper exterior block walls. The core assembly 10, 12, 13, 14, and 16 is then.

however, in practice, a metal flask of more conventional design would be used. Withthe flask closed as viewed in FIGURE 4, it is ready to receive molten metal to start the casting process.

Referring in more detail to FIGURE 1, the crankcasebarrel core unit shown is adapted for use in casting a 90 eight cylinder internal combustion engine. Obviously the type of engine or the number of cylinders is not a limitation to this invention, and the concepts hereof can be readily adapted by modifying the core assembly for use in malcing a V-6 or even an inline engine block. The core 10 being for a V-type engine has a plurality of aligned core body portions 27 of generally triangular shape appropriate to define the crankthrow areas below the engine cylinders. The engine cylinders are cored by the integrally formed barrel core portions 28 and 29' projecting from the triangular side walls 30 f the body portions 27 forming left and right inclined parallel rows. In this case, the left barrel core. portions 28 are arranged in a V-fashion at 90 to the night barrel core portions 29. The barrel core portions have conical bores 31 the function of which will be described hereinafter. The body portions 27 are not separate units but are formed together as a unitary member having generally vertically extending recesses bounded by inner adjacent laterally extending transverse surfaces 32 and being joined locally at the corners by the longitudinally extending leg portions 34 on either side at the bottom and by the cam shaft gallery core portion 35 at the top. The inner adjacent walls or surfaces 32 of the body portions 27. cooperate with the slab 20 in the drag half of the mold 18 to define the bulkhead and bearing structure of the engine block. Accurate portions 36 at the bases of the body portions 27 mate with the longitudinally extending crown 37 of the slab 20 to confine the molten metal within the spaces between the adjacent body portions 27. When the main core is assembled with the end cores 14 and 16, the end walls of the outer core body portions 27 will be spaced. from the inner walls of the end cores by core projections such as 38 on the front core 16, this projection forming the cam shaft opening in the front wall of the block. A similar projection (not shown) on the rear core 14 is also provided. The spacing between the cores 10, 14, and 16 will be sufiicient to define the end walls of the block while the triangular side walls 30 of the body portions 27 will form the interior right and left bank walls of the upper crankcase region through which the cylinders open. The rear core 14 has a recess 39 which partially surrounds the vertical projection 40 on the core 10 being spaced sufliciently therefrom to form a distributor boss in the top of the block.

The water jacket cores 12 and 13 are assembled over the barrel portions 28 and 29 of the core 10 and include generally cylindrical body portions 42 having interior cylindrical walls 43 which are of larger dimension than the barrel portions 28 and 29 so that when arranged in coaxiai relationship therewith there will be a radial spac- 4 'ing between them. This radial spacing, :whichconforms to the engine cylinder barreis,is established by virtue of, the core straps 44 and depending posts 45 which mate. with the conical bores 31 of the barrel co-re portions as bestseen in :FIGURE4. A fit' of the posts and bo-resis reached whenthe tops of" the barrelicore portions abut against the undersurfiaceof the straps 44 automatically locanngthe water jacket. cores in spacial relationship with respect to the crankcase-barrel core unit 10. A core locating function is also performed by the core bosses 46 which project from the lower sides of the cylindrical portions 42 and bear against the inclined green sand walls 47. of the drag. These bosses form openings in the. finished casting that are closed by sheet metal plugs in the well known mannen: Passages 48 opening ,at the top of.

the straps 44 extend down into the posts 45 opening at the other endwithin the bores 31 to vent the core 10 through passages 49 in the cope.

This arrangement of locating the water jacket cores for a V-type engine core assembly is a departure from i the past practice taught, for example; by the Do'lza et a1. patent. There a plurality ofmetallic spacer sleeves are used to, properly space the water jacket cores from the barrel core portions. These sleeves are preferably slightly conical in shape and their smallest internai diameters are somewhat smaller than the outside diameterofthe barrel- Thus whenit-he spacer sleeves are assembled. over the barrel portions, the outward taper of their inner surfaces prevents their sliding downward on the barrel. portions to :an excessive extent with the .result that their;

portions.

lower edges are spacially separated from the sloping side surfaces of the body portions of the crankcase-barrel cores.

When the spacer sleeves are securely inposition around I the barrel portions, the two water jacket cores are placed over the sleeves. and the barrel portions so that the latter protrude completely throughthe openings formed by the cylindrical body portions of the .water jacket core. After assemblyxof the cores in the drag, the spacer sleeves are then removed since the positioning of the .water jacket cores with respect to the barrel core portions is now main-:

tained by core prints in the mold.

In the present invention, the need for metallic spacer sleeves is. eliminated, and instead this function is per formed by the integrally formed core straps 44 and posts 45. It maybe appreciated that the radial spacing'of the water. jacket core is extremely criticalsince a slight. misalignment will cause a thin metal region to form be-.

ing of the Water jacket cores depended primarily upon,

the core prints formed in the drag when ramming the sand around the pattern. It might be appreciated that slight pattern wear in the area of these core prints may cause a considerable error to be introduced with the result that the water jacket cores would be allowed to- Alsoithe use of a large float out of position slightly. number of metallic chaplets to reduce the tendency of the cores to float has been common practice.

-To eliminate these causes of poor castings and to facilitate core setting in the invention, the dependency on,

green sand core prints'is reduced and the: use of chaplets is also reduced. For example, the front end core 16:

has core print recesses 50 on opposite sides thereof to receive the core projections 51 formed on the ends of the water jacket cores; Hence there is no problem of trying to match green sand core prints: in" the drag up with separate core projections when'setting the core assembly wherein the past, a number of core projections were seated in the drag and had to be aligned individually when replacing the core assembly. Proper longitudinal positioning of the core assembly 10, 12, 13, 1'4, and 16 in the drag 1-8 is insured by the core print 52 in the green sand on the left side of the drag wall which cooperates with a small projection (not shown) on the left leg 34 of the crankcase-barrel core to locate the entire core assembly with respect to the drag cavity, the recesses 54 and 56 in the drag being shaped to receive the end cores 14 and 16 respectively. The flask pins 26 serve to locate the cope over the drag; and with the flask in the closed position, as shown in FIGURE 4, ready to receive molten metal, it is seen that the straps 44 engage surfaces in the cope to prevent floating of the cores during casting.

Sprue openings (not shown) extend from the top of the flask down through the cope and drag, cooperating in the drag with channels 59 in the back side of the rear core 14 and the channels 58 in the drag 18 to open into the longitudinal runners 60 formed in the drag below each leg 34 of the crankcase-barrel core 10. As seen in FIGURE 4, gates 62 on the inner edges of the runners 60 open upwardly into the spaces between adjacent body portions 2 7 and between the end cores 14 and 16 and core 10 permitting molten metal to rise into the mold cavity at the engine bulkhead and end wall locations. The gate and runner system is rammed up with the green sand of the drag.

As taught by the Dolza et al. patent, separate crankcase-barrel core units for a V-type engine block are arranged one behind the other in the drag, being mutually spaced from one another by integrally formed core projections which engage the rear surface of the immediately preceeding crankcase-barrel core thereby defining the lower surfaces of the engine bulkheads. These crankcase-barrel cores must be separately formed lying on their sides in a core box having a parting line in a plane passing horizontally through the center. Since the core box opens in a direction normal to this plane and each crankcase-barrel core is a separate unit, it is possible therefore to form the bulkhead bottom surface core projections on the sides of the body portions normal to the parting line. 1

It is important to note that in the present invention, the crankcase-barrel core '10 is a one piece construction in which each bulkhead of the engine is defined in the space between adjacent body portion 27 and the green sand of the rammed portion in the drag. A core box of the type used to form the separate crankcase-barrel core units in Dolza with the parting plane passing generally through the axes of the cylinders could not be used to manufacture the core 10 for the reason that a plurality of body portions and integral barrel portions 27, 28, and 29 are all joined together as a unit, one behind the other in aligned fashion.

To deal with'the problem of manufacturing an integrated crankcase-barrel core such as that shown in FIG- URE 1, I have developed the novel core box illustrated in FIGURES 5 and 6 which includes a plurality of core box sections, some of which are movable with respect to others which are fixed; the movable sections moving relative to each other and to the fixed sections to define a closed cavity of the configuration of the core 10* as shown in FIGURE 5.

Referring to FIGURE 5, the core box 70 is shown in the closed position and includes a vertically movable cover section 72 positioned above a fixed base section 74 which provides a surface 75 to support obliquely slidable barrel forming side sections 76 and a mold surface 89 for forming a portion of the camshaft gallery core portion 35. The side sections 76 have longitudinal bearing surfaces 78 which mate with complementary bearing surfaces 79 on the cover section in the closed position. Stripper plates 80 fixed to the base section 74 extend parallel to the back surfaces 82 of the side sections 76 and are spaced therefrom sufliciently to be out of range when the side sections are moved to the open position. The back surfaces 82 have a plurality of ports 84- which are aligned with ports 85 in the tops of the barrel forming molds 86. The aligned ports 84 and 85 are adapted to receive ejection pins 88 mounted on the fixed stripper plates 80. Blow tubes 90 formed in a cover section 72 communicate with the sand hopper of a standard core blowing machine for introducing the core sand mixture into the mold cavity under air pressure, filling the cavity with tightly packed core sand. The air pressure is exhausted through air vents (not shown) in the right and left barrel molds and the base section. As seen by inspection, the core 10 is formed upside down in the core box which may then be shuttled over gas burners heating the core box and core sand mixture to the baking temperature. After baking, the core box is opened by raising the cover section 72 and retracting right and left barrel forming sections 7 6 relative to the ejection pins 88 which are stationary and extend into the barrel forming molds 86 as shown in FIGURE 6.

The relative positions of the movable core box sections are best shown in FIGURE 6 where the barrel forming side sections 76 have been moved downwardly and outwardly relative to the top section 72 which has been previously raised vertically. Of course to close the box, the sequence is merely reversed; that is, the side sections are first moved to the closed position and then the cover section is lowered.

The core box projections on the cover section 72 form the interior spaces of the main core 10 and include the blades 92 which define the core spaces between the body portions 27, such spaces forming the bulkhead and hearing regions of the engine block. The point here is that no core projections can be allowed on the inner adjacent surfaces 32 of the main core 10 since this would interfere with :the pulling of the blades 92 from between such surfaces. In addition, some redesigning of the engine bulkhead construction is necessary in order to take into account the fact that there must be sufficient draft in the surfaces 32 in order to pull the blade projections.

In other words, the inner adjacent side surfaces 32 must open downwardly and outwardly with respect to a transverse plane which is the plane of the cross section in FIG- URE 5 but passing generally through the center of the bulkhead spaces. This is one way of saying that these surfaces must be free of any projections or pockets and re-entrant angles which would otherwise prevent the pulling of the core box projections. With the design of the engine accordingly modified, as dictated by the foundry practice disclosed here, it is now possible .to join the core body portions and barrel core portions into a one piece crankcase-barrel core unit.

Having now described the invention in its preferred embodiment and in sufficient detail to allow the same to be practised, it is intended that obvious changes may be made, such as modifying the invention to accommodate engine blocks having a different number of cylinders or the like, without deviating therefrom as defined in the appended claims.

I claim:

1. A molding assembly including a flask having a cope and a drag cooperating to form a mold cavity appropriate to define the exterior surface configurations of a multicylinder internal combustion engine frame adapted to be cast therein, a core assembly adapted for use with the flask and being positionable in the mold cavity in spacial relationship with wall portions thereof to define interior surface configurations of the engine frame, said core assem bly comprising a plurality of associated core elements including a unitized crankcase core having a plurality of aligned core body portions formed together as a unit but being locally spaced apart to expose the inner adjacent side surfaces thereof, other surfaces of the core body portions being engageable with surfaces within the mold cavity and cooperating with said side surfaces to define the bulkhead and bearing structure for the engine frame, said inner adjacent side surfaces opening downwardly and outwardly in rectilinear fashion with respect to a vertical s transverse plane through the center of the bulkhead spaces and being characterized by the absence of projections or reentrant angles and pockets, and cylinder barrel core portions being integrally formed with the core body portions and projecting therefrom in planes generally parallel to the transverse planes passing through the bulkhead spaces.

2. A molding assembly including a flask having a cope and a drag cooperating to form a mold cavity appropriate to define the exterior surface configurations of a multicylinder internal combustion engine frame adapted to be cast therein, a core assembly adapted for use with the flask and being positionable in the mold cavity in spacial relationship with wall portions thereof to define interior surface configurations of the engine frame, said core assembly comprising a plurality of associated core elements with the core body portions and projecting therefrom in planes generally parallel to the transverse planes passing through the bulkhead spaces; and

a water jacket core having body portions positionable adjacent said cylinder barrel core portions in spaced relationship thereto and to said core body portions and mold cavity walls, and core extension means formed thereon being engageable with said cylinder barrel core portions for supporting said water jacket" core and for maintaining the spacial relationship thereof during casting.

3. A molding assembly including a flask having a cope and a drag cooperating to for-m a mold cavity appropriate to define the exterior surface configurationsofa V-type multi-cylinder internal combustion engine frame adapted to be cast therein, a core assembly adapted for use in the flask and being positionable in the mold cavity in spacial relationship with wall portions thereof to define interior surface configurations'of the engine frame, said core assembly comprising a plurality of associated core elements including a unitized crankcase core having a plurality of aligned core body portions of generally triangular shape formed together as a unit but being locally spaced apart to expose the inner adjacent side surfaces thereof, other surfaces of the core body portions being engageable with surfaces ,within the mold cavity and cooperating with said side surfaces to define the bulkhead and bearing structurefor the engine frame, said inner adjacent side surfaces of the core body portions opening downwardly and outwardly in rectilinear fashion with respect to a vertical transverse plane through the center of the bulkhead spaces and being characterized by the absence of projections or reentrant angles and pockets, and inclined cylinder barrel" core portions integrally formed with the core body portions and projecting from the triangular side surfaces thereof in planes generally parallel to the transverse planes passing through the bulkhead spaces forming parallel inclined barrel core rows.

'4. A molding assembly including a flask having a cope and a drag cooperating to form a mold cavity appropriate to define the exterior surface configurations of a V-ktype multi-cylinder internal combustion engine frame adapted to be cast therein, a core assembly adapted for use in the flask and being positionable in the mold cavity in spacial relationship with wall portions thereof to define interior 8 surface configurations of the engine frame, said core assembly comprising ,a plurality of associated coreelements including:

a unitized crankcase core having a plurality of aligned core body portions of generally triangular shapefor-med together as a unitbut being :lo'cal-ly spaced apartto expose- *theinner, adjacent side surf-aces thereof, other surfaceslof the core body portions being enga-gegable with surfaceswithin the mold cavity and; cooperating with: said side'. ,surfacesto define the bulkhead and bearing structure for the engine frame, said inner adjacent-side surfaces of the core body portions opening downwardly and outwardly in rec-.

tilinear fashion with respect to the vertical transverse plane through the center of the bulkhead spaces, and inclined cylinder barrel core portions integrally formed with the core body portions and projecting from the triangular side-surfaces thereof in planes generally parallel to the transverse planes passing; through 'therbulkhe'ad spaces forming parallel inclined barrel core rows; and r a pair of water jacket coreseach being, positionable adjacent a barrel core row and having generally cylin drical body portions adapted to surround each said cylinder barrel core portion in spaced relationship thereto and to said core body portions and mold cavity walls, and core extension means formed thereon adapted for engagement with said cylinder barrel core portions and the walls of themold cavity for supporting said water'jacket core and for maintaina ing the spacial relationship thereof during casting.

5.;A molding assembly according to claim 4-Wherein the cylinder barrel core portions have axially formed openings therein and said coreextension means comprise a cross strap formed between opposite sides of said cylindrical body portions being engageable with the mold cavity and havingcentrally depending projections formed thereon'being engageable with said openings in the barrel 1 core portions;

6; A five piece sand core assembly adapted for use with a green sand mold including a cope and a drag cooperating to form a moldcavi-ty appropriate to define the outer surfaceconfiguration of a V-type multi-cylinder internal 2' combustion engineuframe adapted to be cast therein, said 2 core assembly comprising a plurality of associated core elements including.

a crankcase core unit positionable in the-drag and" having a plurality of aligned core bodyportions of generally triangular shapeformed together as a unit but being locally spacedhto expose inner adjacent side surfaces thereof, the bottom surfaces of the core body vportionsbeing engageable with a surface in the green sand of the drag and cooperating with said side surfaces to define the bulkhead and bearing structure for the engine frame, said inner adjacent side surfaces of the core body portionsbeing characterized E by the absence of projections or re-entrant angles:

and pockets;

inclinedcylinder barrel core portions integrally formed withthe core body portions and projecting from the triangular side surfaces thereof in planes generally parallel to the transverse planes passing through the bulkhead spaces forming parallel inclined barrel core 1 rows; a pairiof water jacket cores each being positionable adjacent a barrel core row and having a generally cylindricaljbody'portion adapted to surround each said cylinder barrel core portion in spaced relation ship thereto and. tosaid core body portions and mold cavity walls, core-extensions means, formed thereon being engageable with the cylinder barrel core portions for supporting thewater. jacket cores, and for maintaining the spacial relationship thereof during casting and second core extension means formed integrally with the water jacket cores and projecting forwardly therefrom; and

References Cited by the Examiner UNITED STATES PATENTS 1,432,665 10/1922 Campbell 22-13 10 Demmle-r 22-13 Stoney 22-165 Kulieke 22165 Daniel et a1 2210 Dolza et all 22-131 Leach 22--131 Schueler 221O Kolbe et a1 22-131 0 J. SPENCER OVERHOLSER, Primal) Examiner.

MARCUS U. LYONS, Examiner. 

4. A MOLDING ASSEMBLY INCLUDING A FLASK HAVING A COPE AND A DRAG COOPERATING TO FORM A MOLD CAVITY APPROPRIATE TO DEFINE THE EXTERIOR SURFACE CONFIGURATIONS OF A V-TYPE MULTI-CYLINDER INTERNAL COMBUSTION ENGINE FRAME ADAPTED TO BE CAST THEREIN, A CORE ASSEMBLY ADAPTED FOR USE IN THE FLASK AND BEING POSITIONABLE IN THE MOLD CAVITY IN SPACIAL RELATIONSHIP WITH WALL PORTIONS THEREOF TO DEFINE INTERIOR SURFACE CONFIGURATIONS OF THE ENGINE FRAME, SAID CORE ASSEMBLY COMPRISING A PLURALITY OF ASSOCIATED CORE ELEMENTS INCLUDING: A UNITIZED CRANKCASE CORE HAVING A PLURALITY OF ALIGNED CORE BODY PORTIONS OF GENERALLY TRIANGULAR SHAPE FORMED TOGETHER AS A UNIT BUT BEING LOCALLY SPACED APART TO EXPOSE THE INNER ADJACENT SIDE SURFACES THEREOF, OTHER SURFACES OF THE CORE BODY PORTIONS BEING ENGAGEABLE WITH SURFACES WITHIN THE MOLD CAVITY AND COOPERATING WITH SAID SIDE SURFACES TO DEFINE THE BULKHEAD AND BEARING STRUCTURE FOR THE ENGINE FRAME, SAID INNER ADJACENT SIDE SURFACES OF THE CORE BODY PORTIONS OPENING DOWNWARDLY AND OUTWARDLY IN RECTILINEAR FASHION WITH RESPECT TO THE VERTICAL TRANSVERSE PLANE THROUGH THE CENTER OF THE BULKHEAD SPACES, AND INCLINED CYLINDER BARREL CORE PORTIONS INTEGRALLY FORMED WITH THE CORE BODY PORTIONS AND PROJECTING FROM THE TRIANGULAR SIDE SURFACES THEREOF IN PLANES GENERALLY PARALLEL TO THE TRANSVERSE PLANES PASSING THROUGH THE BULKHEAD SPACES FORMING PARALLEL INCLINED BARREL CORE ROWS; AND A PAIR OF WATER JACKET CORES EACH BEING POSITIONABLE ADJACENT A BARREL CORE ROW AND HAVING GENERALLY CYLINDRICAL BODY PORTIONS ADAPTED TO SURROUND EACH SAID CYLINDER BARREL CORE PORTION IN SPACED RELATIONSHIP THERETO AND TO SAID CORE BODY PORTIONS AND MOLD CAVITY WALLS, AND CORE EXTENSION MEANS FORMED THEREON ADAPTED FOR ENGAGEMENT WITH SAID CYLINDER BARREL CORE PORTIONS AND THE WALLS OF THE MOLD CAVITY FOR SUPPORTING SAID WATER JACKET CORE AND FOR MAINTAINING THE SPACIAL RELATIONSHIP THEREOF DURING CASTING. 